Evacuation method for motor operated valves lubricant

ABSTRACT

A method for removing lubricant grease from enclosed gear train housings of motor operated valve, having one or more ports. First, bulk lubricant grease in the housing is removed by suction through an evacuation wand inserted into the housing. Second, remaining lubricant grease in the housing is mechanically dislodged and physically dissolved by flushing the housing with a solvent for the lubricant grease delivered through a fluid lance inserted into the housing. Third, any lubricant grease/solvent residue in the housing is removed by evacuation through one or more ports in the housing. The method can include rinsing the housing interior and partially drying the housing interior prior to any relubrication. The method can optionally include measuring and analyzing quantities of lubricant grease removed from the housing. A variety of flexible evacuation wands for use in the method can be easily attached to the source of the suction. 
     A fluid lance for use in the method can be an oscillating head, multi-port lance that automatically advances and retracts. The lance has a frame having a perforated drum head disposed of at one end of the frame. A rotating pneumatic motor is connected to the lance shaft via a rocker arm and cam causing oscillation of the lance parallel to the shaft of the motor. A channel in the lance from the handle thereof through the shaft to the drum is adapted for the passage of fluid through the handle and motor to the drum, permitting injection of a fluid through the oscillating drum at elevated temperatures or pressures or both.

This application is a continuation-in-part of Ser. No 158,455 filed Feb.22, 1988, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to cleaning of enclosed gear train housings,particularly motor operated valve gear train housings and moreparticularly to methods and devices for cleaning and removing lubricantfrom such gear train housings without disassembly of the gear train.

Enclosed gear trains are used in conjunction with motor operated valves.A motor operated valve is a valve that is operated by a series of gears,which can be driven by a motor. The motor can be electric, pneumatic, orhydraulic, although the most prevalent type is an electric motor. Thegears are chosen based on the application of the valve. The motoroperated valve is used for the quick, remote operation of valves and forthe operation of large valves. It can be actuated by manual applicationof power to the motor or by automatic application of power. The motoroperated valve can also be manually operated using a hand wheel.

Motor operated valves can be obtained as motor operators. A motoroperator can comprise a valve, a motor, a gear train, a torque limitingmechanism and a housing therefor. Such a motor operator combination isavailable commercially under the trademark LIMITORQUE, for nuclear powerplant applications. The motor operator can function as follows: Anelectric motor turns the gears which amplify the torque to a pointnecessary to drive the valve stem between open and closed positions. Thetravel of the valve stem can be limited by limit switches and/or torquelimiting (sensing) mechanisms that may be contained in or on theoperating mechanism housing which contains the gears. Normally, the samelubricant that lubricates the gears also lubricates the torque limitingmechanism.

Motor operated valves generally operate on a non-continuous cycle. Thevalve operating mechanisms, such as LIMITORQUE, may be used to drive avariety of types and sizes of valves. These valves are normally usedwhere remote control is necessary or desirable. Gear reduced high torquemotors for this purpose are used in highly critical services such as innuclear and other power plants, refineries, space vehicle launchfacilities and the like.

Lubricants, normally heavy greases which may include complex chemicals,are used to lubricate the gear trains. The lubricant for use in a motoroperated valve system is typically a grease which adheres to the gearsand any torque limiting mechanism without the need for an external forceto keep the grease in place on the gears and other mechanisms duringnormal operating conditions. As a result, the lubricating greases foruse under ambient conditions are typically semi-solid or more consistentunder ambient conditions. In general, the semi-solid or thicker greasesare used for motor operated valves, namely, ones having a grade asmeasured by ASTM consistency grade 85-115 or more or NationalLubricating and Grease Institute (NLGI) consistency grade of 6 or less.A preferred lubricant for use in the LIMITORQUE mechanism used innuclear power plants is one having an NLGI grade equal to 0; forexample, the grease sold as Nebula EPO (Exxon). In general, the grade ofgrease used is specified by the manufacturer of the motor operator. Theterm "lubricant grease" used here thus refers to a lubricant ofnaturally occurring and/or synthetic components having a consistency attemperatures and pressures under which the lubricant is used, i.e.,under ambient conditions such that the lubricant grease adheres to thelubricated components without the need for an external force to containthe grease on the components to be lubricated. Lubricant grease isdistinguished from a lubricant oil, which is unsuitable for use with amotor operated valve which requires a more consistent lubricant andwhose housing would not retain the oil.

Over time, the lubricating capacity of the lubricants is reduced due todegradation resulting from radiation, age, humidity and other knowncauses. It is thus necessary to remove the lubricant from the gear trainhousing to facilitate relubrication. Relubrication can improve thepredictability and life of the gear train. Improper valve operation orfailure, which can be precipitated by reduced operability or failure ofthe gear drive due to inadequate lubrication, can cause unacceptablelevels of risk or maintenance shutdown of the facility.

The ability, desire and means of effectively removing a large percentageof the lubricant from a motor operated valve or other heavy mechanicalgear train housing is substantially influenced by the purpose of thegear train, the cost of facility shutdown for cleaning, hazards toservice personnel, including radiation and steam or chemical explosion,alternatives to lubrication and relubrication and the risk of improperassembly if the valve gear train housing is open and disassembled toeffect cleaning and inspection.

The enclosed gear train housings for motor operated valves or otherheavy mechanical gear train housings used in commercial applications aretypically cleaned and relubricated by removing the gear housing from thevalve to a shop for disassembly or to disassemble the gear train inplace and relubricate. Disassembly requires that the valve be out ofoperation for extended periods of time. This lack of operation resultsin the inability to operate other systems and equipment. Further,disassembly can result in incorrect reassembly.

The invention described herein provides an inexpensive and quickalternative for cleaning enclosed gear train housings for motor operatedvalves, in situ, without disassembling the gear train, which comprisescleaning the gear train housing in situ by removing bulk lubricant bysuction, as an optional step, dislodging and dissolving any remaininglubricant with a fluid lance containing solvent for the lubricant, thenremoving any remaining lubricant/solvent mixture.

U.S. Pat. Nos. 1,549,952, 1,696,100, 2,011,811 and 3,308,840 alldescribe devices for automobile gear casings and other enclosed systemsof automobiles. The gear lubricants used for automobile systems areliquids. The efficiency of the cleaning, namely, how much of the spentlubricant is removed, is not particularly critical in an automobilesystem. The lubricant used within a gear train housing for a motoroperated valve is a grease. The difference in form is due to the factthat the gears involved are high torque gears requiring thicklubricants, in a solid or semi-solid form rather than liquid form. Inaddition, because these motor operated valves are used in essentialservices such as nuclear and other power plants, refineries, spacevehicle launch facilities and the like, where lubricant failure canresult in shutdown of the facility, it is absolutely essential thatcleaning efficiency be greater than 90% and preferably almost 100%. Thecited prior art does not use in-place cleaning for enclosed gear trainsof motor operated valves or high torque gears which utilize a lubricantgrease. It has been surprisingly found that the method of this inventioncan have a cleaning efficiency in excess of 99%.

U.S. Pat. No. 2,685,347 and French Patent No. 2,025,982 relate tocleaning of gear cases in oil field applications. Here again, thelubricant is an oil, as seen from the passage in column 1, lines 11-15,of U.S. Pat. No. 2,685,347.

U.S. Pat. Nos. 2,691,380, 4,361,282 and 4,479,612 all relate to varioustypes of flushing tools. U.S. Pat. No. 2,665,772 relates to alubrication system having a pressured feed and suction. U.S. Pat. No.3,585,654 relates to a quick-disconnect joining element.

SUMMARY OF THE INVENTION

A method of removing lubricant grease from an enclosed gear trainhousing of a motor operated valve in which the housing contains at leastone aperture in communication with the lubricated surfaces comprisingthe steps of (a) optionally inserting an evacuation wand into thehousing, and removing lubricant grease by application of suction throughthe evacuation wand, (b) inserting fluid injection apparatus into saidhousing, (c) supplying fluid solvent to said fluid injection apparatusand (d) establishing a fluid solvent stream from said fluid injectionapparatus to the interior of said housing to physically remove saidlubricant, and (e) removing any remaining solvent/lubricant. The methodcan be used with a new high pressure fluid lance, which comprises alance, including an oscillating head and a handle at the other end, aninterior bore extending through the length from the head to the handle,a pneumatic cylinder for advance and withdrawal, a plurality ofapertures in said head, and a pneumatic motor connected to said lance bya rocker arm and cam; and a passageway from said opening in said handlefor passage of a fluid under pressure from said handle through saidlance into said head and outward therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the flexible evacuation wand.

FIG. 2 is a schematic drawing of the valve lubricant recovery vacuumsystem.

FIG. 3 is a plan view of the oscillating high pressure lance showing itsrelationship to the gear train housing prior to insertion.

FIG. 4 is a schematic drawing of the solvent recirculation system.

FIG. 5 is a schematic drawing of the drying air system.

FIG. 6 through 9 are schematic drawings of the motor operator within thegear train housing of FIGS. 2 and 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and particularly to FIG. 1, a perspectiveview of the evacuation wand is shown. Use of the evaluation wand toevacuate bulk solvent is an optional step in the method of thisinvention. Use of this optional step tends to reduce the amount ofsolvent or time needed to dissolve the lubricant in the next step. Theevacuation wand comprises a frame 1 having an interior bore 2, a head atone end and a full port quick disconnect 4 at the other end. At one endof frame 1 is a flexible suction tube 3, axially disposed within thehead of frame 1 and extending through the interior bore 2 of frame 1 tothe full port quick disconnect 4. Disposed a the opposite end of frame 1connected to full port quick disconnect 4 is vacuum hose 5. Disposed atthe other end of vacuum hose 5 is a full port quick disconnect, which isconnected to the vacuum system shown in FIG. 2.

Suction tube 3 of the evacuation wand illustrated in FIG. 1 is sized toenter the access holes 29 and 31 found on enclosed gear trains for motoroperated valves, as more fully described in FIG. 2.

The evacuation wand can be manually manipulated to contact the entrainedlubricant.

FIG. 2 is a schematic drawing of the valve lubricant recovery vacuumsystem of this invention.

The valve gear train housing 30 is shown in FIG. 2. For clarity, thegear train which lies within the housing is not shown in theillustration.

The valve gear train housing 30 of FIG. 2 contains at least one port 29,which can serve as an entry port for the lance shown in FIG. 3, and atleast one opening 31, which can serve as a drain. A vacuum pump 21 takesa suction on waste tank 24 and causes lubricant to pass through theevacuation wand 1 through vacuum hose 5 and be deposited in the wastetank liner 23 for disposal. By manipulation of isolation valves 27 anunadulterated sample of lubricant can be trapped in sample collectionvial 25 for further analysis.

Motor operated valve gear train housings normally contain ports 29 whichserve in normal operation for entry of valve position actuators, usedwith position indicators, in limit switch panels, all of which are notillustrated in the figures. Removal of the valve position indicatorsprovides access to ports 29 for use as lance entry ports. Any coveringsfor openings 31 used in normal operations are removed in preparation forcleaning.

The lance of FIG. 3 is sized to provide for easy access by its head 70shown in FIG. 3.

The lance of FIG. 3 comprises a lance frame 79. The interior of theframe 79 contains a channel 81 through which a lance 72 can pass. Thelance 72 can accept an adaptive fixture 71 which contains a tube 80 andintegral lance head 70. The channel 82 through which fluid can pass,extends from a self-sealing disconnect 73 through to lance head 70, andcontains a plurality of apertures through which fluid can pass.

The lance 72 is advanced into and retracted from the valve gear trainhousing using the air cylinder 76. During advancement and retraction thelance 72 is oscillated by air motor 77 via a rocker ar 78 and cam 75.

Following optional removal of the bulk lubricant with the evacuationwand shown in FIG. 1, as shown as FIG. 2, remaining lubricant is removedusing the fluid lance of FIG. 3. Specifically, a solvent for thelubricant is supplied via the lance of FIG. 3, as shown in FIG. 4, thelance 72 is inserted into limit access switch holes. The lubricantsolvent is then supplied to the lance and then applied to the interiorof the housing to mechanically break up and partially, or totally,dissolve any remaining lubricant so that the lubricant can be readilyevacuated from the gear train housing.

Referring to FIG. 2, in cleaning the enclosed gear train housing 30, theevacuation wand of FIG. 1 is used to remove bulk lubricant. The wandshown in FIG. 1 is inserted into ports 29 and 31 of valve gear trainhousing 30.

The evacuation wand of FIG. 1, in place as shown in FIG. 2 is actuatedto remove the bulk lubricant. Referring to FIG. 1, the suction tube ofthe evacuation wand is sized to fit through holes 31 and to extend intothe valve gear train housing 30 shown in FIG. 2. The wand assembly ofFIG. 1 includes a quick disconnect mounting 4, which is connected to thevacuum system, as shown in FIG. 2, via hose 5 of FIG. 2.

Referring to FIG. 2, bulk lubricant is optionally removed from valvegear train housing 30 by application of the vacuum pump to theevacuation wand of FIG. 1 via hose 5, which is connected to fitting 4shown in FIG. 1.

Referring also to FIG. 2, the bulk lubricant is removed from the valvegear train housing 30 via hose 5 into waste tank 24, which has integralremovable disposable liner 23 and a removable top 32. Vacuum is providedby mechanical vacuum pump 21, capable of producing vacuum pressures of 2to 26 inches of mercury at high volume flows. The exhaust of the vacuumpump 21 is processed through filter/flame arrestor 20 to preventdischarge of entrained lubricant in the exhaust system, which can resultin fire or explosion. A check valve 33 prevents back flow of air.Alternatively, a single three-way valve incorporating valves 34 and 111can be used to isolate the solvent tank from the wate tank. Then whenthe waste tank is on line, back pressure is minimized. Manual valve 34isolates the pump. Vacuum gauge 22 provides information on the conditionof the system.

The evacuation wand, in addition to being used for removing bulksolvent, can be used to remove the residues formed by other processesused in the gear train housing.

Following the removal of bulk lubricant from the gear train housing, thehousing must be injected with acceptable light solvent or other cleaningsolution to remove remaining lubricant, which removal is facilitated bythe use of the oscillating high pressure lance of FIG. 3. The purpose ofthe lance is to mechanically break up and partially or totally dissolvethe remaining lubricant so that it can be readily evacuated from thegear train housing.

The lance 72 is an oscillating lance with a perforated head 70, as seenin FIG. 3, which, when oscillated radially and filled with solvent underelevated pressure, will spray small streams of pressurized solventthroughout the gear train housing 30 to mechanically break or dissolveremaining lubricant. The perforated head is sealed at one end, andfitted with a hollow shaft 72 and 80. A flexible hose 105 and quickdisconnect coupling 106 provide for rapid attachment to the solventinjection system shown in FIG. 4.

The lance 72 is advanced and retracted using air cylinder 76, which issupplied by a control air system. The stroke of air cylinder 76 is sizedto permit full penetration of valve gear train housing 30. During theadvance and withdrawal cycle the lance head 70 and lance shaft areoscillated by air motor 77 via rocker arm 78 and cam 75. Air motor 77 issupplied by control air such that it provides oscillation speedequivalent of 25 to 200 revolutions per minute.

The location and number of perforations in lance head 70 are installedto achieve very high (100-200 psig (pounds per square inch aboveatmospheric pressure)) perforation pressure in routine operation.

Referring to FIG. 4, the solvent 109, which may be a petroleum aliphaticsolvent for petroleum based heavy machinery lubricants (Varsol 18,Humble Oil and Refining) or other cleaning solvents approved by theowner for the service, is pumped to the gear train housing 30 throughlance head 70 by an air driven solvent pump 103. A pressure relief valve108 is provided to prevent over pressurization of hose 105. Pressuregauge 104 permits monitoring of solvent pump 103 output. Self-sealingquick disconnect 106 connects the hose to the lance shaft and permitssolvent to reach the lance head.

Solvent that is introduced into the valve gear train housing throughlimit switch access hole 29 exits through access drain holes 31 anddrains back into the solvent tank 102. The motive force can be gravityor vacuum assisted by vacuum pump 21. The exhaust of the vacuum pump 21passes through filter/flame arrestor 20 to prevent discharge ofentrained solvent in the exhaust system, which can result in fire orexplosion. A check valve 110 prevents back flow of air. Manual valve 111isolates the pumps. Vacuum gauge 100 provides information on thecondition of the vacuum system.

When the solvent becomes saturated with lubricant, it can be drainedthrough valve 101 and the tank refilled through valve 112.

Some applications may require a dynamic system to remove solvent vaporsand remaining liquids. This must be done with a suitable carrier (hotdry air) with an ability (in certain cases) to assure that the hotsolvent-vapor-laden exhaust will not ignite or explode.

A drying air system shown in FIG. 5 may be supplied to achieve theseobjectives. The drying air injection system of FIG. 5 includes afilter/drier 145, regulator 144, electric air heater 143, and dischargehose 141 to deliver dry hot air to the gear train housing 30 through theexistent fill and drain ports 31 or other appropriate entry points.

The hot solvent vapor in the gear train housing 30 is maintained at apressure less than that of the ambient environment through use of ablower 147. The drying air exhaust system consists of outlet lines 131to a blower 133, and flame arrestor 146. Associated pressure andtemperature gauges are provided to assure safe efficient operation. Theair is educated by the blower and the gases discharged through the flamearrestor.

FIGS. 6 through 9 are schematic drawings of the motor operator withinthe gear train housing of FIGS. 2 and 4. The motor operator shown issold under the trademark LIMITORQUE SMB-00 and has special applicationfor use with valves for fluids used in nuclear power plants.

FIGS. 6 to 9 show a front view, in-section of the gear train housing ofthe motor operator within the valve gear train housing shown in FIGS. 2and 4. Referring to FIG. 6, the motor operator is multi-cavitied andcontains various cavities 120, 122, 124, 126 and 128. Cavity 120 inoperation contains the spring pack used with the motor operator. Thespring pack is removed prior to delubrication and relubrication. Cavity122 contains a hand wheel used to operate the valve. Cavity 126 is themain cavity of the valve. Cavity 126 communicates with the motor used toopen and close the valve when the valve is in use. The main cavity 124terminates in a lower bearing 130. The spring pack cavity 120 terminateson its upper portion with an upper bearing 132. FIG. 7 shows a path ofthe fluid solvent used to clean the housing when inserted into theaperatures 29 and 31 of the gear train housing 30, using lance 79, asshown in FIG. 4. The solvent can be removed through drain ports 31,shown in FIG. 7, as well as additional drain ports in the mechanism notshown in the drawing of FIG. 7.

FIG. 8 illustrates the position of limit switch access holes 29 withreference to the cavities, as well as additional patterns for solventflow from the lance 79 through holes 29, into the cavities 120, 122,124, 126, and 128.

FIG. 9 also illustrates a solvent path.

While preferred forms of this invention have been specificallyillustrated and described herein, it will be apparent to those skilledin the art that other modifications and improvements may be made to theforms herein specifically disclosed. Accordingly, the present inventionis not to be limited to the forms herein specifically disclosed, or inany other way inconsistent with the progress in the art promoted by thisinvention.

What is claimed is:
 1. A method of removing lubricant grease beingsemi-solid or more consistent under ambient conditions, without the needof an external force to contain the same and having a NationalLubricating and Grease Institute consistency of less than six from anenclosed multi-cavity gear train housing of a motor operated valve inwhich the housing contains at least one aperture in communication withlubricated surfaces comprising the steps of:inserting fluid injectionpowered to deliver fluid under elevated pressures, to cyclically advanceand retract or to oscillate and to deliver streams of fluid apparatusinto said housing; supplying fluid solvent to said fluid injectionapparatus; establishing a fluid solvent stream from said fluid injectionapparatus to the interior of said housing to physically remove saidlubricant grease; and evacuating any remaining lubricant grease andsolvent from the housing.
 2. A method of removing lubricant grease beingsemi-solid or more consistent under ambient conditions, without the needof an external force to contain the same and having a NationalLubricating and Grease Institute consistency of less than six from anenclosed multi-cavity gear train housing of a motor operated valve inwhich the housing contains at least one aperture in communication withlubricated surfaces comprising the steps of:inserting an evacuation wandinto said housing, said evacuation wand having an internal boreextending substantially the length of the wand, with one end of the boreat one end of the wand and the opposite end of the bore adapted tocommunicate with a source of suction; removing lubricant grease throughone end of the wand by application of suction through a bore in theopposite end of the wand; inserting fluid injection powered to deliverfluid under elevated pressures, to cyclically advance and retract or tooscillate and to deliver streams of fluid apparatus into said housing;supplying fluid solvent to said fluid injection apparatus; establishinga fluid solvent stream from said fluid injection apparatus to theinterior of said housing to physically remove said lubricant grease; andevacuating any remaining lubricant grease and solvent from the housing.3. The method of claim 2, in which the fluid solvent is injected atelevated pressure.
 4. The method of claim 2 in which the fluid solventis injected at elevated temperatures.
 5. The method of claim 2, in whichthe fluid injection apparatus has a plurality of apertures and fluidinjection apparatus is oscillated at 25 to 200 revolutions per minute.6. The method of claim 2, in which the housing is dried by circulationof heated air through the housing after removal of the lubricant greaseand solvent mixture.
 7. A method of removing lubricant grease beingsemi-solid or more consistent under ambient conditions, without the needof an external force to contain the same and having a NationalLubricating and Grease Institute consistency of less than six from anenclosed multi-cavity gear train housing of a motor operated valve inwhich the housing contains at least one aperture in communication withlubricated surfaces comprising the steps of:inserting an evacuation wandinto said housing, said evacuation wand having ahead at one end andmeans adapted to communicate with a source of suction at the other end,and having an internal bore extending from the head to the means forcommunicating with the source of suction at the other end; removinglubricant grease through the head of the wand by application of suctionto the bore; inserting fluid injection powered to deliver fluid underelevated pressures, to cyclically advance and retract or to oscillateand to deliver streams of fluid apparatus into said housing, said fluidinjection apparatus having a plurality of apertures for delivery of thefluid into the housing and being capable of oscillating movement;supplying fluid solvent to said fluid injection apparatus under elevatedpressure; establishing a fluid solvent stream from said fluid injectionapparatus under elevated pressure to the interior of said housingthrough the plurality of apertures on the injection apparatus and withoscillating movement of the apparatus during application of the fluidsolvent stream; and evacuation of any remaining lubricant grease andsolvent from the housing.
 8. The method of claim 7 in which the housingis dried by circulation of heating air through the housing after removalof the lubricant grease and solvent mixture.